In view of the increase in food production and environment conservation, there has been expected production of plants having a tolerance against environmental stresses such as salt and an osmotic pressure. Researches on plants having a tolerance against environmental stresses have been made so far, and there have been reported isolation of plants having resistant mutation (see Non-patent Literatures 1 and 2 for example) and imparting of tolerance by overexpression (see Non-patent Literatures 3 and 4 for example).